Feline leukemia virus vaccine

ABSTRACT

The present invention provides a vaccine for feline leukemia virus and methods of making and using the vaccine alone, or in combinations with other protective agents.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) of provisionalapplications U.S. Ser. No. 62/582,050 filed Nov. 6, 2017, U.S. Ser. No.62/596,508 filed Dec. 8, 2017, and U.S. Ser. No. 62/599,401 filed Dec.15, 2017, the content of all of which are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to new vaccines for feline leukemia virus.Methods of making and using the vaccine alone or in combinations withother protective agents are also provided.

BACKGROUND

Feline leukemia virus (FeLV) is a retrovirus that infects domestic cats,resulting in significant morbidity and mortality worldwide. Thoughpredominantly transmitted through saliva, FeLV also has been reported tospread through contact with body fluids [Pacitti et al., Vet Rec118:381-384 (1986) doi:10.1136/vr.118.14.381; Levy et al., J Feline MedSurg 10:300-316 (2008) doi:10.1016/j.jfms.2008.03.002]. The clinicalsigns in cats observed during FeLV infections include: cytoproliferativedisorders (lymphoid or myeloid tumors), cytosuppressive disorders(infectious diseases associated with immunosuppression, anemia,myelosuppression), inflammatory disorders, neurological disorders,abortions, and enteritis [Hoover et al., J Am Vet Med Assoc199:1287-1297 (1991); Levy and Crawford, Textbook of Veterinary InternalMedicine, 6th ed (Ettinger S J, Feldman E C., eds.) WB Saunders,Philadelphia, Pa. (2005)]. The prevalence of antigenemia may vary from1-5% in healthy cats to 15-30% in afflicted cats [Hosie et al.Veterinary Records, 128: 293-297 (1989); Braley, Feline Practice 22:25-29 (1994); Malik et al., Australian Veterinary Journal 75:323-327(1997); Arjona et al., Journal of Clinical Microbiology 38:3448-3449(2000)]. FeLV frequently establishes a lasting infection with aconcomitant persistent viremia, often leading to the death of the hostcat.

The RNA genome of FeLV encodes only three genes: (i) an ENV gene, whichencodes the envelope glycoprotein, (ii) a GAG gene, which encodes themajor structural components of the virus, and (iii) a POL gene, whichencodes the RNA polymerase [Thomsen et al., Journal of General Virology73:1819-1824 (1992)]. The FeLV envelope (ENV) gene encodes a gp85precursor protein which is proteolytically processed by one or morecellular enzymes to yield the major envelope glycoprotein gp70 and theassociated transmembrane protein p15E [DeNoronha, et al., Virology85:617-621 (1978); Nunberg et al., PNAS 81:3675-3679 (1983)]. Thetransmembrane protein p15E contains a sequence conserved amonggammaretroviruses with immunosuppressive properties [Mathes et al.,Nature 274:687-689 (1978)]. Recently, The European Medicines Agency'sCommittee for Medicinal Products for Veterinary Use (CVMP) has adopted apositive opinion for a vaccine comprising a recombinant p45FeLV-envelope antigen derived from the gp70 surface glycoprotein of theFeLV subgroup A that is expressed in Escherichia coli as activesubstance. The FeLV envelope glycoprotein is the target of FeLV-specificcytotoxic T cell responses, as well as neutralizing antibodies andaccordingly, one of the major immunogens of FeLV [Flynn et al., J.Virol. 76(5): 2306-2315 (2002)].

A variety of factors, such as the immune status of the host, the age ofthe host, the infecting FeLV strain, the viral load, as well as theroute of the exposure of the FeLV can all affect the ultimate outcome ofthat exposure. At one time veterinarians and researchers classified FeLVinfections in relation to the relative persistence of the concomitantantigenemia, which in the more fortunate cases were a transientantigenemia and/or the elimination of infection. Assays for antigenemiainclude p27 enzyme-linked immunosorbent assay (ELISA), virus isolation,and immunofluorescence assays [Hoover et al., J Am Vet Med Assoc199:1287-1297 (1991); Rojko and Kociba, J Am Vet Med Assoc 199:1305-1310(1991)]. Such tests remain helpful in clinical applications, as well asfor determining whether the clinical disease is a result of an activelycirculating virus.

Four vaccines for FeLV are currently available in the United States,including two whole-virus adjuvanted killed vaccines; a dual-adjuvanted,multiple-antigen vaccine; and a nonadjuvanted, canarypox virus-vectoredvaccine. Notably, different vaccines have been shown to have variousdegrees of efficacy [Sparkes, J Small Anim Pract 38:187-194 (1997)doi:10.1111/j.1748-5827.1997.tb03339.x.]. Earlier studies demonstratedthe efficacy of whole-virus adjuvanted killed vaccines after challenge,including testing vaccinated and unvaccinated cats for viral RNA,proviral DNA, FeLV antibodies, and the p27 antigen [Hines et al., J AmVet Med Assoc 199:1428-1430 (1991); Pedersen, J Vet Intern Med 7:34-39(1993) doi:10.1111/j.1939-1676.1993.tb03166.x.]; Torres et al., VetImmunol Immunopathol 134:122-131 (2010)doi:10.1016/j.vetimm.2009.10.017]. There are limited data evaluating theefficacy of the nonadjuvanted recombinant FeLV vaccine available for use[Stuke et al., Vaccine 32:2599-2603 (2014)doi:10.1016/j.vaccine.2014.03.016].

More recently, the efficacy of two commercially available felineleukemia vaccines, one an inactivated whole-virus vaccine and the othera live canarypox virus-vectored vaccine have been compared following achallenge with virulent feline leukemia virus [Patel et al., Clinicaland Vaccine Immunology 22(7):798-805 (2015)]. In this study thewhole-virus adjuvanted killed vaccine was again found to providesuperior protection against FeLV infection. However, the use ofwhole-virus killed adjuvanted FeLV vaccines has been implicated as onefactor that leads to the development of feline injection-site sarcomas[Kass et al., J. AM Vet Med Assoc 203 (3): 396-405 (1993)]. Althoughsubsequent studies have been unable to establish a direct link betweenkilled adjuvanted vaccines and feline injection-site sarcomas, aperception remains that nonadjuvanted vaccines are safer. Indeed, theAmerican Association of Feline Practitioners Feline VaccinationGuidelines suggest the use of nonadjuvanted FeLV vaccines to lower therisk of feline injection-site sarcomas and to reduce local inflammation[AAFP Feline Advisory Panel, 15: 785-808 (2013)].

A number of vector strategies have been employed through the years forvaccines in an effort to protect against certain pathogens. One suchvector strategy includes the use of alphavirus-derived replicon RNAparticles (RP) [Vander Veen, et al. Anim Health Res Rev. 13(1):1-9.(2012) doi: 10.1017/S1466252312000011; Kamrud et al., J Gen Virol. 91(Pt7):1723-1727 (2010)] which have been developed from several differentalphaviruses, including Venezuelan equine encephalitis virus (VEE)[Pushko et al., Virology 239:389-401 (1997)], Sindbis (SIN) [Bredenbeeket al., Journal of Virology 67:6439-6446 (1993)], and Semliki Forestvirus (SFV) [Liljestrom and Garoff, Biotechnology (NY) 9:1356-1361(1991)]. RP vaccines deliver propagation-defective alphavirus RNAreplicons into host cells and result in the expression of the desiredantigenic transgene(s) in vivo [Pushko et al., Virology 239(2):389-401(1997)]. RPs have an attractive safety and efficacy profile whencompared to some traditional vaccine formulations [Vander Veen, et al.Anim Health Res Rev. 13(1):1-9. (2012)]. The RP platform has been usedto encode pathogenic antigens and is the basis for several USDA-licensedvaccines for swine and poultry.

Unfortunately heretofore, pet owners were forced to choose between (i)nonadjuvanted FeLV vaccines that were believed to be safer, but found tobe significantly less efficacious than killed, adjuvanted vaccines [see,Stuke et al., Vaccine 32: 2599-2603 (2014); Patel et al., Clin VaccineImmunol 22 (7):798-808 (2015)] and (ii) the adjuvanted FeLV vaccines,which though more efficacious, are perceived by some to lead toinjection-site sarcomas. Accordingly, there remains a present need foran improved, safe nonadjuvanted FeLV vaccine, which while not inducingfeline injection-site sarcomas still protects vaccinates from thedebilitating disease state caused by FeLV infection as efficaciously asits inactivated whole-virus adjuvanted vaccine counterpart.

The citation of any reference herein should not be construed as anadmission that such reference is available as “prior art” to the instantapplication.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides vectors that encode one ormore feline leukemia virus (FeLV) antigens. Such vectors can be used inimmunogenic compositions comprising these vectors. The immunogeniccompositions of the present invention may be used in vaccines. In oneaspect of the present invention, a vaccine protects the vaccinatedsubject (e.g., mammal) against FeLV. In a particular embodiment of thistype, the vaccinated subject is a feline. In a more particularembodiment, the vaccinated subject is a domestic cat. The presentinvention further provides combination vaccines for eliciting protectiveimmunity against FeLV and other diseases, e.g., other feline infectiousdiseases. Methods of making and using the immunogenic compositions andvaccines of the present invention are also provided.

In specific embodiments, the vector is an alphavirus RNA repliconparticle that encodes one or more antigens that originate from a felinepathogen. In particular embodiments, the feline pathogen is FeLV. Inmore particular embodiments, the alphavirus RNA replicon particlesencode a FeLV glycoprotein (gp85). In related embodiments, thealphavirus RNA replicon particles encode an antigenic fragment of gp85.In a particular embodiment of this type, the antigenic fragment of gp85is the FeLV glycoprotein gp70. In certain related embodiments, theantigenic fragment of gp85 is the FeLV glycoprotein gp45. In still moreparticular embodiments, the alphavirus RNA replicon particle is aVenezuelan Equine Encephalitis (VEE) alphavirus RNA replicon particle.In yet more specific embodiments the VEE alphavirus RNA repliconparticle is a TC-83 VEE alphavirus RNA replicon particle. In otherembodiments, the alphavirus RNA replicon particle is a Sindbis (SIN)alphavirus RNA replicon particle. In still other embodiments, thealphavirus RNA replicon particle is a Semliki Forest virus (SFV)alphavirus RNA replicon particle. In an alternative embodiment a nakedDNA vector comprises a nucleic acid construct that encodes one or moreantigens that originate from a feline pathogen. In particularembodiments of this type, the naked DNA vectors comprise a nucleic acidconstruct that encodes a FeLV gp85, or antigenic fragment thereof.

In certain embodiments an alphavirus RNA replicon particle of thepresent invention encodes one or more FeLV antigens or antigenicfragments thereof. In particular embodiments of this type, thealphavirus RNA replicon particles encode two to four FeLV antigens orantigenic fragments thereof. In other embodiments, immunogeniccompositions comprise alphavirus RNA replicon particles that encode oneor more FeLV antigens or antigenic fragments thereof. In relatedembodiments, the immunogenic compositions comprise alphavirus RNAreplicon particles encodes two to four FeLV antigens or antigenicfragments thereof. In particular embodiments of this type, thealphavirus RNA replicon particles encode an FeLV glycoprotein (gp85) oran antigenic fragment thereof. In more particular embodiments of thistype, the antigenic fragment of gp85 is the FeLV glycoprotein gp70. Incertain related embodiments, the antigenic fragment of gp85 is the FeLVglycoprotein gp45. In more particular embodiments, the immunogeniccomposition comprises alphavirus RNA replicon particles that areVenezuelan Equine Encephalitis (VEE) alphavirus RNA replicon particles.In yet more specific embodiments the VEE alphavirus RNA repliconparticles are TC-83 VEE alphavirus RNA replicon particles.

In still other embodiments, the immunogenic composition comprises two ormore sets of alphavirus RNA replicon particles. In particularembodiments of this type, one set of alphavirus RNA replicon particlesencodes a particular antigen, whereas the other set of alphavirus RNAreplicon particles encodes a second antigen. In a specific embodiment ofthis type the first set of alphavirus RNA replicon particles encode theFeLV antigen or an antigenic fragment thereof, and the second set ofalphavirus RNA replicon particles encode a feline calicivirus (FCV)antigen or an antigenic fragment thereof. In certain embodiments of thistype, the FCV antigen originates from a virulent systemic felinecalicivirus (VS-FCV) isolate. In other embodiments the FCV antigenoriginates from a classical (F9-like) feline calicivirus isolate. In yetother embodiments, the second set of alphavirus RNA replicon particlesencode two FCV antigens, one of which originates from a virulentsystemic feline calicivirus isolate, whereas the other originates from aclassical (F9-like) feline calicivirus isolate.

In yet other embodiments, the immunogenic composition comprises one setof alphavirus RNA replicon particles that encode a first antigen,another set of alphavirus RNA replicon particles that encode a secondantigen, and a third set of alphavirus RNA replicon particles thatencode a third antigen. In a particular embodiment of this type, thefirst set of alphavirus RNA replicon particles encode the FeLV antigenor an antigenic fragment thereof, the second set of alphavirus RNAreplicon particles encode a feline calicivirus (FCV) antigen whichoriginates from a virulent systemic feline calicivirus or an antigenicfragment thereof, and the third set of alphavirus RNA replicon particlesencode a feline calicivirus (FCV) antigen which originates from aclassical (F9-like) feline calicivirus or an antigenic fragment thereof.

Accordingly, in particular embodiments in which the immunogeniccompositions comprise multiple sets (e.g., 2-10) of alphavirus RNAreplicon particles, in which the first set of alphavirus RNA repliconparticles encode the FeLV antigen or an antigenic fragment thereof, theone or more other sets of alphavirus RNA replicon particles can encodeone or more non-FeLV antigens. In certain embodiments of this type, thenon-FeLV antigen is a protein antigen that originates from felineherpesvirus (FHV). In other embodiments, the non-FeLV antigen is aprotein antigen that originates from feline calicivirus (FCV). In yetother embodiments, the non-FeLV antigen is a protein antigen thatoriginates from feline pneumovirus (FPN). In still other embodiments,the non-FeLV antigen is a protein antigen that originates from felineparvovirus (FPV). In yet other embodiments, the non-FeLV antigen is aprotein antigen that originates from feline infectious peritonitis virus(FIPV). In still other embodiments, the non-FeLV antigen is a proteinantigen that originates from feline immunodeficiency virus. In stillother embodiments, the non-FeLV antigen is a protein antigen thatoriginates from borna disease virus (BDV). In yet other embodiments, thenon-FeLV antigen is a protein antigen that originates from felineinfluenza virus. In still other embodiments, the non-FeLV antigen is aprotein antigen that originates from feline panleukopenia virus (FPLV).In yet other embodiments the non-FeLV antigen is a protein antigen thatoriginates from feline coronavirus (FCoV). In still other embodimentsthe non-FeLV antigen is a protein antigen that originates from felinerhinotracheitis virus (FVR). In yet other embodiments the non-FeLVantigen is a protein antigen that originates from Chlamydophila felis.

The present invention also includes all of the nucleic acid constructsof the present invention including synthetic messenger RNA, RNAreplicons, as well as all of the alphavirus RNA replicon particles ofthe present invention, the naked DNA vectors, and the immunogeniccompositions and/or vaccines that comprise the nucleic acid constructs(e.g., synthetic messenger RNA, RNA replicons), the alphavirus RNAreplicon particles, and/or the naked DNA vectors of the presentinvention.

In particular embodiments, a nucleic acid construct of the presentinvention encodes one or more FeLV antigens or antigenic fragmentsthereof. In related embodiments of this type, the nucleic acid constructencodes two to four FeLV antigens or antigenic fragments thereof. Inother embodiments, alphavirus RNA replicon particles comprise a nucleicacid construct that encodes one or more FeLV antigens or antigenicfragments thereof. In particular embodiments, alphavirus RNA repliconparticles comprise a nucleic acid construct that encodes two to fourFeLV antigens or antigenic fragments thereof.

In still other embodiments, the immunogenic compositions comprisealphavirus RNA replicon particles that comprise a nucleic acid constructthat encodes two to four FeLV antigens or antigenic fragments thereof.In particular embodiments of this type, the alphavirus RNA repliconparticles comprise a nucleic acid construct encoding an FeLVglycoprotein (gp85) or an antigenic fragment thereof. In a particularembodiment of this type, the antigenic fragment of gp85 is the FeLVglycoprotein gp70. In other related embodiments, the antigenic fragmentof gp85 is the FeLV glycoprotein gp45. In more particular embodiments,the immunogenic composition comprises alphavirus RNA replicon particlesthat are Venezuelan Equine Encephalitis (VEE) alphavirus RNA repliconparticles. In yet more specific embodiments the VEE alphavirus RNAreplicon particles are TC-83 VEE alphavirus RNA replicon particles.

In yet other embodiments, the immunogenic composition comprises two ormore sets of alphavirus RNA replicon particles. In particularembodiments of this type, one set of alphavirus RNA replicon particlescomprises a first nucleic acid construct, whereas the other set ofalphavirus RNA replicon particles comprise a second nucleic acidconstruct. In a specific embodiment of this type the first nucleic acidconstruct encodes the FeLV antigen or an antigenic fragment thereof, andthe second nucleic acid construct encodes a feline calicivirus (FCV)antigen or an antigenic fragment thereof. In certain embodiments of thistype, the FCV antigen originates from a virulent systemic felinecalicivirus (VS-FCV) isolate. In other embodiments the FCV antigenoriginates from a classical (F9-like) feline calicivirus isolate. In yetother embodiments, the second nucleic acid construct encodes two FCVantigens, one of which originates from a virulent systemic felinecalicivirus isolate, whereas the other originates from a classical(F9-like) feline calicivirus isolate.

In still other embodiments, the immunogenic composition comprises oneset of alphavirus RNA replicon particles that comprise a first nucleicacid construct, another set of alphavirus RNA replicon particles thatcomprise a second nucleic acid construct, and a third set of alphavirusRNA replicon particles that comprise a third nucleic acid construct. Ina particular embodiment of this type, the first nucleic acid constructencodes the FeLV antigen or an antigenic fragment thereof, the secondnucleic acid construct encodes a feline calicivirus (FCV) antigen whichoriginates from a virulent systemic feline calicivirus or an antigenicfragment thereof, and the third nucleic acid construct encodes a felinecalicivirus (FCV) antigen which originates from a classical (F9-like)feline calicivirus or an antigenic fragment thereof.

In yet other embodiments, the immunogenic composition comprises one setof alphavirus RNA replicon particles that comprise a first nucleic acidconstruct, another set of alphavirus RNA replicon particles thatcomprise a second nucleic acid construct, a third set of alphavirus RNAreplicon particles that comprise a third nucleic acid construct, and afourth set of alphavirus RNA replicon particles that comprise a fourthnucleic acid construct. In yet other embodiments, the immunogeniccomposition comprises a set of alphavirus RNA replicon particles thatcomprise a first nucleic acid construct, another set of alphavirus RNAreplicon particles that comprise a second nucleic acid construct, athird set of alphavirus RNA replicon particles that comprise a thirdnucleic acid construct, a fourth set of alphavirus RNA repliconparticles that comprise a fourth nucleic acid construct, and a fifth setof alphavirus RNA replicon particles that comprise a fifth nucleic acidconstruct. In such embodiments, the nucleotide sequences of the firstnucleic acid construct, the second nucleic acid construct, third nucleicacid construct, the fourth nucleic acid construct, and the fifth nucleicacid construct are all different.

Accordingly, an immunogenic composition of the present invention cancontain alphavirus RNA replicon particles that comprise a nucleic acidconstruct that encodes at least one non-FeLV antigen for elicitingprotective immunity to a non-FeLV pathogen. In particular embodiments ofthis type, the non-FeLV antigen is a protein antigen that originatesfrom feline herpesvirus (FHV). In other embodiments, the non-FeLVantigen is a protein antigen that originates from feline calicivirus(FCV). In yet other embodiments, the non-FeLV antigen is a proteinantigen that originates from feline pneumovirus (FPN). In still otherembodiments, the non-FeLV antigen is a protein antigen that originatesfrom feline parvovirus (FPV). In yet other embodiments, the non-FeLVantigen is a protein antigen that originates from feline infectiousperitonitis virus (FIPV). In still other embodiments, the non-FeLVantigen is a protein antigen that originates from felineimmunodeficiency virus. In still other embodiments, the non-FeLV antigenis a protein antigen that originates from borna disease virus (BDV). Inyet other embodiments, the non-FeLV antigen is a protein antigen thatoriginates from feline influenza virus. In still other embodiments, thenon-FeLV antigen is a protein antigen that originates from felinepanleukopenia virus (FPLV). In yet other embodiments the non-FeLVantigen is a protein antigen that originates from feline coronavirus(FCoV). In still other embodiments the non-FeLV antigen is a proteinantigen that originates from feline rhinotracheitis virus (FVR). Instill other embodiments the non-FeLV antigen is a protein antigen thatoriginates from Chlamydophila felis.

The present invention further provides combination immunogeniccompositions and/or vaccines (multivalent vaccines) that includealphavirus RNA replicon particles that encode an antigen or antigenicfragment thereof originating from FeLV together with one or moremodified live (e.g., attenuated) or killed feline pathogens. Inparticular embodiments, the immunogenic compositions comprise a modifiedlive or killed Chlamydophila felis combined with alphavirus RNA repliconparticles that encode an antigen or antigenic fragment thereoforiginating from FeLV. In other embodiments, the immunogeniccompositions comprise a modified live or killed feline rhinotracheitisVirus (FVR) combined with alphavirus RNA replicon particles that encodean antigen or antigenic fragment thereof originating from FeLV. In stillother embodiments, the immunogenic compositions comprise a modified liveor killed feline calicivirus (FCV) combined with alphavirus RNA repliconparticles that encode an antigen or antigenic fragment thereoforiginating from FeLV. In yet other embodiments, the immunogeniccompositions comprise a modified live or killed feline panleukopeniavirus (FPL) combined with alphavirus RNA replicon particles that encodean antigen or antigenic fragment thereof originating from FeLV. In stillother embodiments, the immunogenic compositions comprise a modified liveor killed Chlamydophila felis, a modified live or killed FVR, a modifiedlive or killed FCV, a modified live or killed FPL, and alphavirus RNAreplicon particles that encode an antigen or antigenic fragment thereoforiginating from FeLV. In particular embodiments of this type, thefeline antigen of the FeLV is the FeLV viral glycoprotein (gp85). Incertain embodiments, vaccines comprise an immunologically effectiveamount of one or more of these immunogenic compositions.

In particular embodiments the FeLV antigen is the FeLV glycoprotein(gp85). In specific embodiments of this type, the FeLV glycoprotein gp85comprises an amino acid sequence comprising 95% identity or more withthe amino acid sequence of SEQ ID NO: 2. In more specific embodiments ofthis type, the FeLV glycoprotein (gp85) comprises the amino acidsequence of SEQ ID NO: 2. In even more specific embodiments of this typethe FeLV glycoprotein (gp85) is encoded by the nucleotide sequence ofSEQ ID NO: 1 or SEQ ID NO: 10. In related embodiments, the FeLVglycoprotein gp70 comprises an amino acid sequence comprising 95%identity or more with the amino acid sequence of SEQ ID NO: 4. In morespecific embodiments of this type, the FeLV glycoprotein (gp85)comprises the amino acid sequence of SEQ ID NO: 4. In even more specificembodiments of this type the FeLV glycoprotein (gp70) is encoded by thenucleotide sequence of SEQ ID NO: 3 or SEQ ID NO: 11.

The present invention further comprises vaccines and multivalentvaccines comprising the immunogenic compositions of the presentinvention. In particular embodiments, the vaccines are nonadjuvantedvaccine. In certain embodiments, the vaccine aids in the prevention ofdisease due to FeLV. In related embodiments, antibodies are induced in afeline subject when the feline is immunized with the vaccine.

The present invention also provides methods of immunizing a felineagainst a feline pathogen, e.g., FeLV, comprising administering to thefeline an immunologically effective amount of a vaccine or multivalentof the present invention. In particular embodiments the vaccine isadministered via intramuscular injection. In alternative embodiments thevaccine is administered via subcutaneous injection. In other embodimentsthe vaccine is administered via intravenous injection. In still otherembodiments the vaccine is administered via intradermal injection. Inyet other embodiments the vaccine is administered via oraladministration. In still other embodiments the vaccine is administeredvia intranasal administration. In specific embodiments, the feline is adomestic cat.

The vaccines and multivalent vaccines of the present invention can beadministered as a primer vaccine and/or as a booster vaccine. Inspecific embodiments, a vaccine of the present invention is administeredas a one shot vaccine (one dose), without requiring subsequentadministrations. In certain embodiments, in the case of theadministration of both a primer vaccine and a booster vaccine, theprimer vaccine and the booster vaccine can be administered by theidentical route. In certain embodiments of this type, the primer vaccineand the booster vaccine are both administered by subcutaneous injection.In alternative embodiments, in the case of the administration of both aprimer vaccine and a booster vaccine, the administration of the primervaccine can be performed by one route and the booster vaccine by anotherroute. In certain embodiments of this type, the primer vaccine can beadministered by subcutaneous injection and the booster vaccine can beadministered orally.

The invention further provides for a method of immunizing a felineagainst FeLV comprising injecting the feline with an immunologicallyeffective amount of the above described inventive vaccines. Inparticular embodiments the vaccines can include from about 1×10⁴ toabout 1×10¹⁰ RPs or higher, for example. In more particular embodimentsthe vaccines can include from about 1×10⁵ to about 1×10⁹ RPs. In evenmore particular embodiments the vaccines can include from about 1×10⁶ toabout 1×10⁸ RPs. In particular embodiments the feline is a domestic cat.

In particular embodiments the vaccines of the present invention areadministered in 0.05 mL to 3 mL doses. In more particular embodimentsthe dose administered is 0.1 mL to 2 mLs. In still more particularembodiments the dose administered is 0.2 mL to 1.5 mLs. In even moreparticular embodiments the dose administered is 0.3 to 1.0 mLs. In stillmore particular embodiments the dose administered is 0.4 mL to 0.8 mLs.In yet more particular embodiments the dose administered is 0.5 mL to1.5 mLs.

These and other aspects of the present invention will be betterappreciated by reference to the following Detailed Description.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an improved, safe nonadjuvanted FeLVvaccine. In one aspect, the vaccines of the present invention do notinduce feline injection-site sarcomas, yet still provide protection tothe vaccinates from the debilitating disease state caused by FeLVinfection as efficaciously as an inactivated whole-virus adjuvantedvaccine.

Accordingly, the vaccine compositions of the present invention includean immunologically effective amount of a vector encoding an antigen fromone or more strains of feline leukemia virus that aids in elicitingprotective immunity in the recipient vaccinated animal. Furthermore, thepresent invention provides new immunologic compositions to improve thereliability of vaccination to aid in the reduction of antigenemia in afeline infected by FeLV and to thereby yield a transient antigenemiaand/or lead to the elimination of the infection. In a particular aspectof the present invention, the vaccines comprise an alphavirus RNAreplicon particle (RP) encoding the FeLV viral glycoprotein (gp85). Inmore specific embodiments, the vaccines comprise alphavirus RNA repliconparticles (RPs) that comprise the capsid protein and glycoproteins ofVenezuelan Equine Encephalitis Virus (VEE) and encode the FeLV viralglycoprotein (gp85) and/or an antigenic fragment thereof (e.g., gp70 orgp45). In even more specific embodiments, the vaccines comprisealphavirus RNA replicon particles (RPs) that comprise the capsid proteinand glycoproteins of the avirulent TC-83 strain of VEE and encode theFeLV viral glycoprotein (gp85) and/or an antigenic fragment thereof(e.g., gp70 or gp45). In another aspect of the present invention, thevaccines comprise naked DNA vectors that encode the FeLV viralglycoprotein (gp85) and/or an antigenic fragment thereof (e.g., gp70 orgp45). The vaccines of the present invention can be administered to afeline in the absence of an adjuvant and still effectively aid in theprotection of the vaccinated feline against FeLV.

In order to more fully appreciate the invention, the followingdefinitions are provided.

The use of singular terms for convenience in description is in no wayintended to be so limiting. Thus, for example, reference to acomposition comprising “a polypeptide” includes reference to one or moreof such polypeptides. In addition, reference to an “alphavirus RNAreplicon particle” includes reference to a plurality of such alphavirusRNA replicon particles, unless otherwise indicated.

As used herein the term “approximately” is used interchangeably with theterm “about” and signifies that a value is within fifty percent of theindicated value i.e., a composition containing “approximately” 1×10⁸alphavirus RNA replicon particles per milliliter contains from 0.5×10⁸to 1.5×10⁸ alphavirus RNA replicon particles per milliliter.

As used herein, the term “feline” refers to any member of the Felidaefamily. Domestic cats, pure-bred and/or mongrel companion cats, and wildor feral cats are all felines.

As used herein, the term “replicon” refers to a modified RNA viralgenome that lacks one or more elements (e.g., coding sequences forstructural proteins) that if they were present, would enable thesuccessful propagation of the parental virus in cell cultures or animalhosts. In suitable cellular contexts, the replicon will amplify itselfand may produce one or more sub-genomic RNA species.

As used herein, the term “alphavirus RNA replicon particle”, abbreviated“RP”, is an alphavirus-derived RNA replicon packaged in structuralproteins, e.g., the capsid and glycoproteins, which also are derivedfrom an alphavirus, e.g., as described by Pushko et al., [Virology239(2):389-401 (1997)]. An RP cannot propagate in cell cultures oranimal hosts (without a helper plasmid or analogous component), becausethe replicon does not encode the alphavirus structural components (e.g.,capsid and glycoproteins).

The term “non-FeLV”, is used to modify terms such as pathogen, and/orantigen (or immunogen) to signify that the respective pathogen, and/orantigen (or immunogen) is neither an FeLV pathogen nor a FeLV antigen(or immunogen) and that a non-FeLV protein antigen (or immunogen) doesnot originate from an FeLV.

The terms “originate from”, “originates from” and “originating from” areused interchangeably with respect to a given protein antigen and thepathogen or strain of that pathogen that naturally encodes it, and asused herein signify that the unmodified and/or truncated amino acidsequence of that given protein antigen is encoded by that pathogen orstrain of that pathogen. The coding sequence within a nucleic acidconstruct of the present invention for a protein antigen originatingfrom a pathogen may have been genetically manipulated so as to result ina modification and/or truncation of the amino acid sequence of theexpressed protein antigen relative to the corresponding sequence of thatprotein antigen in the pathogen or strain of pathogen (includingnaturally attenuated strains) it originates from.

As used herein, the terms “protecting”, or “providing protection to”, or“eliciting protective immunity to”, “aids in prevention of disease”, and“aids in the protection” do not require complete protection from anyindication of infection. For example, “aids in the protection” can meanthat the protection is sufficient such that, after challenge, symptomsof the underlying infection are at least reduced, and/or that one ormore of the underlying cellular, physiological, or biochemical causes ormechanisms causing the symptoms are reduced and/or eliminated. It isunderstood that “reduced,” as used in this context, means relative tothe state of the infection, including the molecular state of theinfection, not just the physiological state of the infection.

As used herein, a “vaccine” is a composition that is suitable forapplication to an animal, e.g., feline (including, in certainembodiments, humans, while in other embodiments being specifically notfor humans) comprising one or more antigens typically combined with apharmaceutically acceptable carrier such as a liquid containing water,which upon administration to the animal induces an immune responsestrong enough to minimally aid in the protection from a disease arisingfrom an infection with a wild-type micro-organism, i.e., strong enoughfor aiding in the prevention of the disease, and/or preventing,ameliorating or curing the disease.

As used herein, a multivalent vaccine is a vaccine that comprises two ormore different antigens. In a particular embodiment of this type, themultivalent vaccine stimulates the immune system of the recipientagainst two or more different pathogens.

The terms “adjuvant” and “immune stimulant” are used interchangeablyherein, and are defined as one or more substances that cause stimulationof the immune system. In this context, an adjuvant is used to enhance animmune response to one or more vaccine antigens/isolates. Accordingly,“adjuvants” are agents that nonspecifically increase an immune responseto a particular antigen, thus reducing the quantity of antigen necessaryin any given vaccine, and/or the frequency of injection necessary inorder to generate an adequate immune response to the antigen ofinterest. In this context, an adjuvant is used to enhance an immuneresponse to one or more vaccine antigens/isolates. The AmericanAssociation of Feline Practitioners Feline Vaccination Guidelinessuggest the use of nonadjuvanted FeLV vaccines [AAFP Feline AdvisoryPanel, 15: 785-808 (2013)].

As used herein, a “nonadjuvanted vaccine” is a vaccine or a multivalentvaccine that does not contain an adjuvant.

As used herein, the term “pharmaceutically acceptable” is usedadjectivally to mean that the modified noun is appropriate for use in apharmaceutical product. When it is used, for example, to describe anexcipient in a pharmaceutical vaccine, it characterizes the excipient asbeing compatible with the other ingredients of the composition and notdisadvantageously deleterious to the intended recipient animal, e.g.,feline.

Parenteral administration” includes subcutaneous injections, submucosalinjections, intravenous injections, intramuscular injections,intradermal injections, and infusion.

As used herein the term “antigenic fragment” in regard to a particularprotein (e.g., a protein antigen) is a fragment of that protein that isantigenic, i.e., capable of specifically interacting with an antigenrecognition molecule of the immune system, such as an immunoglobulin(antibody) or T cell antigen receptor. For example, an antigenicfragment of an FeLV viral glycoprotein (gp85) is a fragment of the gp85protein that is antigenic. Preferably, an antigenic fragment of thepresent invention is immunodominant for antibody and/or T cell receptorrecognition. In particular embodiments, an antigenic fragment withrespect to a given protein antigen is a fragment of that protein thatretains at least 25% of the antigenicity of the full length protein. Inpreferred embodiments an antigenic fragment retains at least 50% of theantigenicity of the full length protein. In more preferred embodiments,an antigenic fragment retains at least 75% of the antigenicity of thefull length protein. Antigenic fragments can be as small as 20 aminoacids or at the other extreme, be large fragments that are missing aslittle as a single amino acid from the full-length protein. Inparticular embodiments the antigenic fragment comprises 25 to 150 aminoacid residues. In other embodiments, the antigenic fragment comprises 50to 250 amino acid residues. The gp45 glycoprotein and the gp70glycoprotein are antigenic fragments of the gp85 glycoprotein.

As used herein one amino acid sequence is 100% “identical” or has 100%“identity” to a second amino acid sequence when the amino acid residuesof both sequences are identical. Accordingly, an amino acid sequence is50% “identical” to a second amino acid sequence when 50% of the aminoacid residues of the two amino acid sequences are identical. Thesequence comparison is performed over a contiguous block of amino acidresidues comprised by a given protein, e.g., a protein, or a portion ofthe polypeptide being compared. In a particular embodiment, selecteddeletions or insertions that could otherwise alter the correspondencebetween the two amino acid sequences are taken into account.

As used herein, nucleotide and amino acid sequence percent identity canbe determined using C, MacVector (MacVector, Inc. Cary, N.C. 27519),Vector NTI (Informax, Inc. MD), Oxford Molecular Group PLC (1996) andthe Clustal W algorithm with the alignment default parameters, anddefault parameters for identity. These commercially available programscan also be used to determine sequence similarity using the same oranalogous default parameters. Alternatively, an Advanced Blast searchunder the default filter conditions can be used, e.g., using the GCG(Genetics Computer Group, Program Manual for the GCG Package, Version 7,Madison, Wis.) pileup program using the default parameters.

As used herein, the term “inactivated” microorganism is usedinterchangeably with the term “killed” microorganism. For the purposesof this invention, an “inactivated” microorganism is an organism whichis capable of eliciting an immune response in an animal, but is notcapable of infecting the animal. An antigen of the present invention(e.g., an inactivated feline panleukopenia virus) may be inactivated byan agent selected from the group consisting of binary ethyleneimine,formalin, beta-propiolactone, thimerosal, or heat. In a particularembodiment, inactivated feline calicivirus isolates combined with an RPof the present invention are inactivated by binary ethyleneimine.

The alphavirus RNA replicon particles of the present invention may belyophilized and rehydrated with a sterile water diluent. On the otherhand, when the alphavirus RNA replicon particles are stored separately,but intend to be mixed with other vaccine components prior toadministration, the alphavirus RNA replicon particles can be stored inthe stabilizing solution of those components, e.g., a high sucrosesolution.

A vaccine of the present invention can be readily administered by anystandard route including intravenous, intramuscular, subcutaneous, oral,intranasal, intradermal, and/or intraperitoneal vaccination. The skilledartisan will appreciate that the vaccine composition is preferablyformulated appropriately for each type of recipient animal and route ofadministration.

Thus, the present invention also provides methods of immunizing a felineagainst FeLV and/or other feline pathogens. One such method comprisesinjecting a feline with an immunologically effective amount of a vaccineof the present invention, so that the feline produces appropriate FeLVantibodies.

Multivalent Vaccines:

The present invention also provides multivalent vaccines. For example,the coding sequence of a protein antigen or antigenic fragment thereof,or combination of such coding sequences of protein antigens useful in afeline vaccine can be added to an alphavirus RNA replicon particle (RP)or combined in the same RP as one that encodes a feline antigen of theFeLV [e.g., the FeLV viral glycoprotein (gp85)] in the vaccine.Accordingly, such multivalent vaccines are included in the presentinvention.

Examples of pathogens that one or more of such protein antigens canoriginate from include feline rhinotracheitis Virus (FVR), felinecalicivirus (FCV), feline panleukopenia Virus (FPL) feline herpesvirus(FHV), other FeLV strains, feline parvovirus (FPV), feline infectiousperitonitis virus (FIPV), feline immunodeficiency virus, borna diseasevirus (BDV), rabies virus, feline influenza virus, canine influenzavirus, avian influenza, canine pneumovirus, feline pneumovirus,Chlamydophila felis (FKA Chlamydia psittaci), Bordetella bronchiseptica,and Bartonella spp. (e.g., B. henselae). In particular embodiments, acoding sequence for a capsid protein or analogous protein from one ormore of these feline or canine pathogens can be inserted into the sameRP as the FeLV antigen. Alternatively, or in combination therewith, acoding sequence for a capsid protein or analogous protein from one ormore of these feline or canine pathogens can be inserted into one ormore other RPs, which can be combined with the RP that encodes the FeLVantigen in a vaccine.

In addition, an alphavirus RNA replicon particle(RP) that encodes afeline antigen of the FeLV [e.g., the FeLV viral glycoprotein (gp85)]can be added together with one or more other live, attenuated virusisolates such as a live attenuated other FCV strain, a live attenuatedfeline herpesvirus and/or a live attenuated feline parvovirus and/or alive, attenuated feline leukemia virus, and/or a live, attenuated felineinfectious peritonitis virus and/or a live, attenuated felineimmunodeficiency virus and/or a live, attenuated borna disease virusand/or a live, attenuated rabies virus, and/or a live, attenuated felineinfluenza virus and/or a live, attenuated canine influenza virus, and/ora live, attenuated avian influenza, and/or a live, attenuated caninepneumovirus, and/or a live, attenuated feline pneumovirus. In addition,a live, attenuated Chlamydophila felis, and/or a live, attenuatedBordetella bronchiseptica and/or a live, attenuated Bartonella spp.(e.g., B. henselae) can also be included in such multivalent vaccines.

Furthermore, an alphavirus RNA replicon particle (RP) that encodes afeline antigen of the FeLV [e.g., the FeLV viral glycoprotein (gp85)]can be added together with one or more other killed virus isolates suchas a killed FCV strain, and/or a killed feline herpesvirus and/or akilled feline parvovirus and/or a killed feline leukemia virus, and/or akilled feline infectious peritonitis virus and/or a killed felineimmunodeficiency virus and/or a killed borna disease virus and/or akilled rabies virus, and/or a killed feline influenza virus and/or akilled canine influenza virus, and/or a killed avian influenza virus,and/or a killed canine pneumovirus, and/or a killed feline pneumovirus.In addition, bacterins of Chlamydophila felis, and/or Bordetellabronchiseptica and/or Bartonella spp. (e.g., B. henselae) can also beincluded in such multivalent vaccines.

It is also to be understood that this invention is not limited to theparticular configurations, process steps, and materials disclosed hereinas such configurations, process steps, and materials may vary somewhat.

It is also to be understood that the terminology employed herein is usedfor the purpose of describing particular embodiments only and is notintended to be limiting, since the scope of the present invention willbe limited only by the appended claims and equivalents thereof.

SEQUENCE TABLE SEQ ID NO: Description Type 1 FeLV viral glycoprotein(gp85) nucleic acid DNA 2 FeLV viral glycoprotein (gp85) amino acid 3FeLV viral glycoprotein (gp70) nucleic acid DNA 4 FeLV viralglycoprotein (gp70) amino acid 5 Feline Calicivirus (VS-FCV) nucleicacid DNA 6 Feline Calicivirus (VS-FCV) amino acid 7 Feline Calicivirus(F9-like) nucleic acid DNA 8 Feline Calicivirus (F9-like) amino acid 9GGCGCGCCGCACC nucleic acid 10 FeLV viral glycoprotein (gp85) nucleicacid RNA 11 FeLV viral glycoprotein (gp70) nucleic acid RNA 12 FelineCalicivirus (VS-FCV) nucleic acid RNA 13 Feline Calicivirus (F9-like)nucleic acid RNA TTAATTAA nucleic acid

SEQUENCESFeline Leukemia Virus envelope glycoprotein (gp85) SEQ ID NO: 1atggagtcaccaacacaccctaaaccttctaaagacaaaaccctctcgtggaatctcgccttccttgtgggcatcctgttcacaatcgacatcggcatggccaacccttcgccgcatcagatctacaatgtgacatgggtcattactaatgtgcagacaaacacccaggcaaatgctacttctatgcttggtactctgactgatgcttatccaaccctgcacgtcgacctttgcgatctcgtcggtgacacatgggagcccatcgtgctgaatccaactaatgtcaaacatggtgccaggtattcttctagcaaatacgggtgtaagaccactgatcggaagaaacagcaacaaacctacccattctacgtgtgcccgggtcacgcaccgtccctgggtccgaagggaacacattgtgggggagcccaagacggtttttgcgctgcttggggttgtgaaacaaccggagaagcctggtggaagcctacctcatcttgggactacattactgtgaaaagaggctctagccaggataacagctgcgaaggaaagtgtaatcccctggtgcttcaattcacccagaaaggccggcaggcatcatgggatggaccgaaaatgtggggacttagactctatcgcaccggatacgaccccatcgctctgtttactgtgtcacgccaagtctccaccattactccgccacaggccatggggccgaatctggtcctccccgatcagaagccaccctcacggcaaagtcaaaccggctcaaaagtggccacccaacggccccagacaaatgagtccgcacctaggtcagtggcacctacaacaatgggtccaaagcggatcggaaccggagacaggctcattaacctcgtgcaagggacttatctggcccttaacgctactgaccccaacaagaccaaggattgctggctctgccttgtgagcagacctccttactatgaggggatcgccattctcggaaactactcaaatcagaccaacccccctccgtcgtgtctgagcaccccccagcacaagcttactatttcagaagtcagtggacagggaatgtgcatcggaaccgtgccaaagactcatcaagccctttgcaacaaaactcaacaagggcacactggagctcattatctcgccgcacctaacgggacctactgggcttgcaatactggattgaccccgtgtatctctatggccgtgctgaattggacttccgacttctgcgtgcttattgagctttggcctagagtgacataccatcagcctgagtacgtctatacccatttcgccaaggcagtcagattccggcgggagcctatctccctgactgtggccttgatgctcggtggactgacagtgggaggaattgcagctggagtcggaactggaaccaaggccctgctcgaaactgctcagttccggcagctgcagatggccatgcacactgacatccaggctctggaggaatcaatttcagcccttgagaaaagcttgacctcgctgtctgaagtggtcctccaaaacaggcgcggtttggacatcctgttccttcaagagggtggtctgtgcgccgctctcaaggaggaatgctgtttctacgctgaccataccgggctggtgcgcgataacatggcaaagctgcgggaacgcttgaaacagaggcagcaactgttcgactctcagcagggatggttcgagggctggtttaacaagagcccatggtttaccactctgatctcttcaatcatgggtccactgctcatcctgcttctgattcttctcttcggaccgtgtattctcaacaggctggtgcagtttgtcaaggacagaatctcggtggtccaggccctgattcttactcagcagtatcagcagattaagcagtacgaccccgatcggccttgaFeline Leukemia Virus envelope glycoprotein (gp85) SEQ ID NO: 2MESPTHPKPSKDKTLSWNLAFLVGILFTIDIGMANPSPHQIYNVTWVITNVQTNTQANATSMLGTLTDAYPTLHVDLCDLVGDTWEPIVLNPTNVKHGARYSSSKYGCKTTDRKKQQQTYPFYVCPGHAPSLGPKGTHCGGAQDGFCAAWGCETTGEAWWKPTSSWDYITVKRGSSQDNSCEGKCNPLVLQFTQKGRQASWDGPKMWGLRLYRTGYDPIALFTVSRQVSTITPPQAMGPNLVLPDQKPPSRQSQTGSKVATQRPQTNESAPRSVAPTTMGPKRIGTGDRLINLVQGTYLALNATDPNKTKDCWLCLVSRPPYYEGIAILGNYSNQTNPPPSCLSTPQHKLTISEVSGQGMCIGTVPKTHQALCNKTQQGHTGAHYLAAPNGTYWACNTGLTPCISMAVLNWTSDFCVLIELWPRVTYHQPEYVYTHFAKAVRFRREPISLTVALMLGGLTVGGIAAGVGTGTKALLETAQFRQLQMAMHTDIQALEESISALEKSLTSLSEVVLQNRRGLDILFLQEGGLCAALKEECCFYADHTGLVRDNMAKLRERLKQRQQLFDSQQGWFEGWFNKSPWFTTLISSIMGPLLILLLILLFGPCILNRLVQFVKDRISVVQALILTQQYQQIKQYDPDRP*Feline Leukemia Virus envelope glycoprotein (gp85) SEQ ID NO: 10auggagucaccaacacacccuaaaccuucuaaagacaaaacccucucguggaaucucgccuuccuugugggcauccuguucacaaucgacaucggcauggccaacccuucgccgcaucagaucuacaaugugacaugggucauuacuaaugugcagacaaacacccaggcaaaugcuacuucuaugcuugguacucugacugaugcuuauccaacccugcacgucgaccuuugcgaucucgucggugacacaugggagcccaucgugcugaauccaacuaaugucaaacauggugccagguauucuucuagcaaauacggguguaagaccacugaucggaagaaacagcaacaaaccuacccauucuacgugugcccgggucacgcaccgucccuggguccgaagggaacacauugugggggagcccaagacgguuuuugcgcugcuugggguugugaaacaaccggagaagccugguggaagccuaccucaucuugggacuacauuacugugaaaagaggcucuagccaggauaacagcugcgaaggaaaguguaauccccuggugcuucaauucacccagaaaggccggcaggcaucaugggauggaccgaaaauguggggacuuagacucuaucgcaccggauacgaccccaucgcucuguuuacugugucacgccaagucuccaccauuacuccgccacaggccauggggccgaaucugguccuccccgaucagaagccacccucacggcaaagucaaaccggcucaaaaguggccacccaacggccccagacaaaugaguccgcaccuaggucaguggcaccuacaacaauggguccaaagcggaucggaaccggagacaggcucauuaaccucgugcaagggacuuaucuggcccuuaacgcuacugaccccaacaagaccaaggauugcuggcucugccuugugagcagaccuccuuacuaugaggggaucgccauucucggaaacuacucaaaucagaccaaccccccuccgucgugucugagcaccccccagcacaagcuuacuauuucagaagucaguggacagggaaugugcaucggaaccgugccaaagacucaucaagcccuuugcaacaaaacucaacaagggcacacuggagcucauuaucucgccgcaccuaacgggaccuacugggcuugcaauacuggauugaccccguguaucucuauggccgugcugaauuggacuuccgacuucugcgugcuuauugagcuuuggccuagagugacauaccaucagccugaguacgucuauacccauuucgccaaggcagucagauuccggcgggagccuaucucccugacuguggccuugaugcucgguggacugacagugggaggaauugcagcuggagucggaacuggaaccaaggcccugcucgaaacugcucaguuccggcagcugcagauggccaugcacacugacauccaggcucuggaggaaucaauuucagcccuugagaaaagcuugaccucgcugucugaagugguccuccaaaacaggcgcgguuuggacauccuguuccuucaagaggguggucugugcgccgcucucaaggaggaaugcuguuucuacgcugaccauaccgggcuggugcgcgauaacauggcaaagcugcgggaacgcuugaaacagaggcagcaacuguucgacucucagcagggaugguucgagggcugguuuaacaagagcccaugguuuaccacucugaucucuucaaucauggguccacugcucauccugcuucugauucuucucuucggaccguguauucucaacaggcuggugcaguuugucaaggacagaaucucggugguccaggcccugauucuuacucagcaguaucagcagauuaagcaguacgaccccgaucggccuugaFeline Leukemia Virus envelope glycoprotein (gp70) SEQ ID NO: 3aatcctagtccacaccaaatatataatgtaacttgggtaataaccaatgtacaaactaacacccaagctaacgccacctctatgttaggaaccttaaccgatgcctaccctaccctacatgttgacttatgtgacctagtgggagacacctgggaacctatagtcctaaacccaaccaatgtaaaacacggggcacgttactcctcctcaaaatatggatgtaaaactacagatagaaaaaaacagcaacagacataccccttttacgtctgccccggacatgccccctcgttggggccaaagggaacacattgtggaggggcacaagatgggttttgtgccgcatggggatgtgagaccaccggagaagcttggtggaagcccacctcctcatgggactatatcacagtaaaaagagggagtagtcaggacaatagctgtgagggaaaatgcaaccccctggttttgcagttcacccagaagggaagacaagcctcttgggacggacctaagatgtggggattgcgactataccgtacaggatatgaccctatcgctttattcacggtgtcccggcaggtatcaaccattacgccgcctcaggcaatgggaccaaacctagtcttacctgatcaaaaacccccatcccgacaatctcaaacagggtccaaagtggcgacccagaggccccaaacgaatgaaagcgccccaaggtctgttgcccccaccaccatgggtcccaaacggattgggaccggagataggttaataaatttagtacaagggacatacctagccttaaatgccaccgaccccaacaaaactaaagactgttggctctgcctggtttctcgaccaccctattacgaagggattgcaatcttaggtaactacagcaaccaaacaaacccccccccatcctgcctatctactccgcaacacaaactaactatatctgaagtatcagggcaaggaatgtgcatagggactgttcctaaaacccaccaggctttgtgcaataagacacaacagggacatacaggggcgcactatctagccgcccccaacggcacctattgggcctgtaacactggactcaccccatgcatttccatggcggtgctcaattggacctctgatttttgtgtcttaatcgaattatggcccagagtgacttaccatcaacccgaatatgtgtacacacattttgccaaagctgtcaggttccgaagaFeline Leukemia Virus envelope glycoprotein (gp70) SEQ ID NO: 4NPSPHQIYNVTWVITNVQTNTQANATSMLGTLTDAYPTLHVDLCDLVGDTWEPIVLNPTNVKHGARYSSSKYGCKTTDRKKQQQTYPFYVCPGHAPSLGPKGTHCGGAQDGFCAAWGCETTGEAWWKPTSSWDYITVKRGSSQDNSCEGKCNPLVLQFTQKGRQASWDGPKMWGLRLYRTGYDPIALFTVSRQVSTITPPQAMGPNLVLPDQKPPSRQSQTGSKVATQRPQTNESAPRSVAPTTMGPKRIGTGDRLINLVQGTYLALNATDPNKTKDCWLCLVSRPPYYEGIAILGNYSNQTNPPPSCLSTPQHKLTISEVSGQGMCIGTVPKTHQALCNKTQQGHTGAHYLAAPNGTYWACNTGLTPCISMAVLNWTSDFCVLIELWPRVTYHQPEYVYTHFAKAVRFRRFeline Leukemia Virus envelope glycoprotein (gp70) SEQ ID NO: 11aauccuaguccacaccaaauauauaauguaacuuggguaauaaccaauguacaaacuaacacccaagcuaacgccaccucuauguuaggaaccuuaaccgaugccuacccuacccuacauguugacuuaugugaccuagugggagacaccugggaaccuauaguccuaaacccaaccaauguaaaacacggggcacguuacuccuccucaaaauauggauguaaaacuacagauagaaaaaaacagcaacagacauaccccuuuuacgucugccccggacaugcccccucguuggggccaaagggaacacauuguggaggggcacaagauggguuuugugccgcauggggaugugagaccaccggagaagcuugguggaagcccaccuccucaugggacuauaucacaguaaaaagagggaguagucaggacaauagcugugagggaaaaugcaacccccugguuuugcaguucacccagaagggaagacaagccucuugggacggaccuaagauguggggauugcgacuauaccguacaggauaugacccuaucgcuuuauucacggugucccggcagguaucaaccauuacgccgccucaggcaaugggaccaaaccuagucuuaccugaucaaaaacccccaucccgacaaucucaaacaggguccaaaguggcgacccagaggccccaaacgaaugaaagcgccccaaggucuguugcccccaccaccaugggucccaaacggauugggaccggagauagguuaauaaauuuaguacaagggacauaccuagccuuaaaugccaccgaccccaacaaaacuaaagacuguuggcucugccugguuucucgaccacccuauuacgaagggauugcaaucuuagguaacuacagcaaccaaacaaacccccccccauccugccuaucuacuccgcaacacaaacuaacuauaucugaaguaucagggcaaggaaugugcauagggacuguuccuaaaacccaccaggcuuugugcaauaagacacaacagggacauacaggggcgcacuaucuagccgcccccaacggcaccuauugggccuguaacacuggacucaccccaugcauuuccauggcggugcucaauuggaccucugauuuuugugucuuaaucgaauuauggcccagagugacuuaccaucaacccgaauauguguacacacauuuugccaaagcugucagguuccgaagaFeline Calicivirus (VS-FCV) capsid (SEQ ID NO: 5)atggctgacgacggatctgtgaccaccccagaacaaggaacaatggtcggaggagtgattgccgaacccagcgctcagatgtcaactgcggcggacatggcctccggaaagtcggtggactccgagtgggaagccttcttctcgttccacacgtccgtgaactggagcacctccgaaacccaaggaaagatcctcttcaagcagtccctgggtcccctgctgaacccgtacctggagcacatcagcaagctgtacgtcgcttggagcgggtcgatcgaagtgcgattttccatctcgggaagcggcgtgttcggtggtaaactggccgccatcgtcgtgccgcctggtgtcgaccctgtccagtcaacctccatgctgcagtacccgcacgtcctgttcgacgcaagacaagtggagccagtgatcttctccatcccggacctccgcaacagcctgtatcacttgatgtccgataccgataccacttccctcgtgatcatggtgtacaacgatctgatcaacccgtacgccaatgactccaacagctcgggttgcatcgtgaccgtcgaaacgaagcctggcatcgatttcaagtttcatctgctgaaaccgcccggatccatgcttactcacgggtccatcccttccgatctgatccccaagagctcctccctgtggattgggaaccgccactggaccgatattaccgatttcgtgattcggcctttcgtgttccaagccaaccggcacttcgacttcaaccaggagactgccggctggtcaactccacggttccgcccattggccgtgactgtgtcgcagtcaaagggagccaagctcgggaacggcatcgccaccgactacattgtgcctggaatccccgacggatggcctgatactaccatccccaccaagctgacccctaccggagattacgccatcacctcctccgacggcaatgatattgaaaccaagctggaatacgagaacgcggacgtgattaagaacaacaccaacttccgctccatgtatatctgcggaagcctccagagggcttggggcgacaagaagatcagcaacaccgggttcatcactaccggagtgatttctgacaactccatcagcccttcgaacacaattgaccagtccaagatcgtggtgtaccaggacaaccatgtcaattcggaggtccagactagcgacatcactcttgccatcctgggctacaccggaattggagaagaggccataggcgccaaccgggactccgtcgtgagaatttccgtgcttccggaaactggagcaaggggcggaaatcaccccatcttctacaaaaattccatgaagctgggctacgtgatctcctccattgacgtgttcaactcccaaatcctccacacctcgcgccagctgtcactgaacaactacttgttgccccctgactccttcgcggtgtaccggattattgacagcaacggatcatggttcgacattgggattgacagcgatgggttttcattcgtgggcgtgtcgtcatttccaaagctggagtttccgctgtccgcctcatacatgggcatccagctcgcaaagatccggctggcgtccaacatccggtcatccatgactaagctgtga Feline Calicivirus (VS-FCV) capsid (SEQ ID NO: 6)MADDGSVTTPEQGTMVGGVIAEPSAQMSTAADMASGKSVDSEWEAFFSFHTSVNWSTSETQGKILFKQSLGPLLNPYLEHISKLYVAWSGSIEVRFSISGSGVFGGKLAAIVVPPGVDPVQSTSMLQYPHVLFDARQVEPVIFSIPDLRNSLYHLMSDTDTTSLVIMVYNDLINPYANDSNSSGCIVTVETKPGIDFKFHLLKPPGSMLTHGSIPSDLIPKSSSLWIGNRHWTDITDFVIRPFVFQANRHFDFNQETAGWSTPRFRPLAVTVSQSKGAKLGNGIATDYIVPGIPDGWPDTTIPTKLTPTGDYAITSSDGNDIETKLEYENADVIKNNTNFRSMYICGSLQRAWGDKKISNTGFITTGVISDNSISPSNTIDQSKIVVYQDNHVNSEVQTSDITLAILGYTGIGEEAIGANRDSVVRISVLPETGARGGNHPIFYKNSMKLGYVISSIDVFNSQILHTSRQLSLNNYLLPPDSFAVYRIIDSNGSWFDIGIDSDGFSFVGVSSFPKLEFPLSASYMGIQLAKIRLASNIRS SMTKLFeline Calicivirus (VS-FCV) capsid (SEQ ID NO: 12)auggcugacgacggaucugugaccaccccagaacaaggaacaauggucggaggagugauugccgaacccagcgcucagaugucaacugcggcggacauggccuccggaaagucgguggacuccgagugggaagccuucuucucguuccacacguccgugaacuggagcaccuccgaaacccaaggaaagauccucuucaagcagucccuggguccccugcugaacccguaccuggagcacaucagcaagcuguacgucgcuuggagcgggucgaucgaagugcgauuuuccaucucgggaagcggcguguucggugguaaacuggccgccaucgucgugccgccuggugucgacccuguccagucaaccuccaugcugcaguacccgcacguccuguucgacgcaagacaaguggagccagugaucuucuccaucccggaccuccgcaacagccuguaucacuugauguccgauaccgauaccacuucccucgugaucaugguguacaacgaucugaucaacccguacgccaaugacuccaacagcucggguugcaucgugaccgucgaaacgaagccuggcaucgauuucaaguuucaucugcugaaaccgcccggauccaugcuuacucacggguccaucccuuccgaucugauccccaagagcuccucccuguggauugggaaccgccacuggaccgauauuaccgauuucgugauucggccuuucguguuccaagccaaccggcacuucgacuucaaccaggagacugccggcuggucaacuccacgguuccgcccauuggccgugacugugucgcagucaaagggagccaagcucgggaacggcaucgccaccgacuacauugugccuggaauccccgacggauggccugauacuaccauccccaccaagcugaccccuaccggagauuacgccaucaccuccuccgacggcaaugauauugaaaccaagcuggaauacgagaacgcggacgugauuaagaacaacaccaacuuccgcuccauguauaucugcggaagccuccagagggcuuggggcgacaagaagaucagcaacaccggguucaucacuaccggagugauuucugacaacuccaucagcccuucgaacacaauugaccaguccaagaucgugguguaccaggacaaccaugucaauucggagguccagacuagcgacaucacucuugccauccugggcuacaccggaauuggagaagaggccauaggcgccaaccgggacuccgucgugagaauuuccgugcuuccggaaacuggagcaaggggcggaaaucaccccaucuucuacaaaaauuccaugaagcugggcuacgugaucuccuccauugacguguucaacucccaaauccuccacaccucgcgccagcugucacugaacaacuacuuguugcccccugacuccuucgcgguguaccggauuauugacagcaacggaucaugguucgacauugggauugacagcgauggguuuucauucgugggcgugucgucauuuccaaagcuggaguuuccgcuguccgccucauacaugggcauccagcucgcaaagauccggcuggcguccaacauccggucauccaugacuaagcuguga Feline Calicivirus (F9-like) capsid (SEQ ID NO: 7)atgactgccccggaacaaggaacgatggtcggaggagtgattgcagaaccgtcagcacagatgtccaccgctgccgacatggccactggaaagagcgtggactccgaatgggaagccttcttctccttccacacttcggtcaactggtcgactagcgaaacccaggggaagattttgttcaagcaatccctcggccctctgctgaacccctacctggagcatctggccaagctgtacgtggcatggtcgggcagcatcgaagtgcgctttagcatttccggctccggagtgttcgggggaaagcttgctgccattgtcgtgccgccaggagtggacccggtgcagtccacttctatgctccaatacccgcatgtcctgttcgacgccagacaggtggagcctgtgatcttttgcctgccggatctcaggtccaccctgtatcacctcatgtccgacaccgacaccacctcgctcgtgatcatggtgtacaacgacctgatcaacccctacgctaacgacgccaacagctcaggttgcattgtgactgtcgaaaccaagccaggccctgacttcaagtttcatttgctgaagccgcccggttccatgctgacccacggctcgatcccatccgacctgatccccaagacgagctccctgtggatcggaaaccgctactggtccgatattaccgacttcgtgatcagaccattcgtgttccaagccaaccgccatttcgacttcaaccaggaaaccgcaggatggtcgacccctcgattccgcccgatttcagtgaccatcaccgaacagaacggcgcgaagctgggaattggcgtggcgaccgactacatcgtgccgggaatcccggatggatggcctgatacgaccattcccggggagctgatccctgccggggactacgccatcaccaacggtactggaaacgacatcaccactgccaccggttacgacaccgccgacatcataaagaacaacaccaacttcagaggaatgtacatttgcggctccctgcaacgcgcttggggtgacaaaaagatctcgaacactgccttcatcacaacagcgactctggacggcgataacaacaacaagatcaatccttgtaataccatcgaccagtccaaaatcgtggtgttccaggataaccacgtgggaaagaaggcgcagacctccgacgacactctggcgctgcttggctacaccgggatcggcgagcaggccattggaagcgatcgggatcgggtcgtgcggatctccaccctccccgagactggagcaaggggaggcaaccaccccatcttttacaaaaacagcattaagctcggatacgtcatccgctccatcgatgtgttcaactctcaaatcctgcacacttcgcggcagctgtccctgaaccactacctcttgccgcccgactccttcgccgtctaccggatcattgattcgaacgggagctggttcgacatcggcattgatagcgatggcttctcgtttgtgggcgtgtcgggcttcgggaagctggagttcccactgagcgcctcatacatgggtatccagctggccaagatcaggctggcctccaacatccgctcacctatgact aagctgtgaFeline Calicivirus (F9-like) capsid (SEQ ID NO: 8)MTAPEQGTMVGGVIAEPSAQMSTAADMATGKSVDSEWEAFFSFHTSVNWSTSETQGKILFKQSLGPLLNPYLEHLAKLYVAWSGSIEVRFSISGSGVFGGKLAAIVVPPGVDPVQSTSMLQYPHVLFDARQVEPVIFCLPDLRSTLYHLMSDTDTTSLVIMVYNDLINPYANDANSSGCIVTVETKPGPDFKFHLLKPPGSMLTHGSIPSDLIPKTSSLWIGNRYWSDITDFVIRPFVFQANRHFDFNQETAGWSTPRFRPISVTITEQNGAKLGIGVATDYIVPGIPDGWPDTTIPGELIPAGDYAITNGTGNDITTATGYDTADIIKNNTNFRGMYICGSLQRAWGDKKISNTAFITTATLDGDNNNKINPCNTIDQSKIVVFQDNHVGKKAQTSDDTLALLGYTGIGEQAIGSDRDRVVRISTLPETGARGGNHPIFYKNSIKLGYVIRSIDVFNSQILHTSRQLSLNHYLLPPDSFAVYRIIDSNGSWFDIGIDSDGFSFVGVSGFGKLEFPLSASYMGIQLAKIRLASNIRSPMT KLFeline Calicivirus (F9-like) capsid (SEQ ID NO: 13)augacugccccggaacaaggaacgauggucggaggagugauugcagaaccgucagcacagauguccaccgcugccgacauggccacuggaaagagcguggacuccgaaugggaagccuucuucuccuuccacacuucggucaacuggucgacuagcgaaacccaggggaagauuuuguucaagcaaucccucggcccucugcugaaccccuaccuggagcaucuggccaagcuguacguggcauggucgggcagcaucgaagugcgcuuuagcauuuccggcuccggaguguucgggggaaagcuugcugccauugucgugccgccaggaguggacccggugcaguccacuucuaugcuccaauacccgcauguccuguucgacgccagacagguggagccugugaucuuuugccugccggaucucagguccacccuguaucaccucauguccgacaccgacaccaccucgcucgugaucaugguguacaacgaccugaucaaccccuacgcuaacgacgccaacagcucagguugcauugugacugucgaaaccaagccaggcccugacuucaaguuucauuugcugaagccgcccgguuccaugcugacccacggcucgaucccauccgaccugauccccaagacgagcucccuguggaucggaaaccgcuacugguccgauauuaccgacuucgugaucagaccauucguguuccaagccaaccgccauuucgacuucaaccaggaaaccgcaggauggucgaccccucgauuccgcccgauuucagugaccaucaccgaacagaacggcgcgaagcugggaauuggcguggcgaccgacuacaucgugccgggaaucccggauggauggccugauacgaccauucccggggagcugaucccugccggggacuacgccaucaccaacgguacuggaaacgacaucaccacugccaccgguuacgacaccgccgacaucauaaagaacaacaccaacuucagaggaauguacauuugcggcucccugcaacgcgcuuggggugacaaaaagaucucgaacacugccuucaucacaacagcgacucuggacggcgauaacaacaacaagaucaauccuuguaauaccaucgaccaguccaaaaucgugguguuccaggauaaccacgugggaaagaaggcgcagaccuccgacgacacucuggcgcugcuuggcuacaccgggaucggcgagcaggccauuggaagcgaucgggaucgggucgugcggaucuccacccuccccgagacuggagcaaggggaggcaaccaccccaucuuuuacaaaaacagcauuaagcucggauacgucauccgcuccaucgauguguucaacucucaaauccugcacacuucgcggcagcugucccugaaccacuaccucuugccgcccgacuccuucgccgucuaccggaucauugauucgaacgggagcugguucgacaucggcauugauagcgauggcuucucguuugugggcgugucgggcuucgggaagcuggaguucccacugagcgccucauacauggguauccagcuggccaagaucaggcuggccuccaacauccgcucaccuaugacu aagcugugaThe following examples serve to provide further appreciation of theinvention but are not meant in any way to restrict the effective scopeof the invention.

EXAMPLES Example 1 Incorporation of the Coding Sequences for FeLV GP85into the Alphavirus RNA Replicon Particles Introduction

RNA viruses have been used as vector-vehicles for introducing vaccineantigens, which have been genetically engineered into their genomes.However, their use to date has been limited primarily to incorporatingviral antigens into the RNA virus and then introducing the virus into arecipient host. The result is the induction of protective antibodiesagainst the incorporated viral antigens. Alphavirus RNA repliconparticles have been used to encode pathogenic antigens. Such alphavirusreplicon platforms have been developed from several differentalphaviruses, including Venezuelan equine encephalitis virus (VEE)[Pushko et al., Virology 239:389-401 (1997)], Sindbis (SIN) [Bredenbeeket al., Journal of Virology 67:6439-6446 (1993) the contents of whichare hereby incorporated herein in their entireties], and Semliki Forestvirus (SFV) [Liljestrom and Garoff, Biotechnology (NY) 9:1356-1361(1991), the contents of which are hereby incorporated herein in theirentireties]. Moreover, alphavirus RNA replicon particles are the basisfor several USDA-licensed vaccines for swine and poultry. These include:Porcine Epidemic Diarrhea Vaccine, RNA Particle (Product Code 19U5.P1),Swine Influenza Vaccine, RNA (Product Code 19A5.D0), Avian InfluenzaVaccine, RNA (Product Code 1905.D0), and Prescription Product, RNAParticle (Product Code 9PP0.00).

Alphavirus RNA Replicon Particle Construction

An amino acid sequence for FeLV gp85 were used to generatecodon-optimized (feline codon usage) nucleotide sequences in silico.Optimized sequences were prepared as synthetic DNA by a commercialvendor (ATUM, Newark, Calif.). Accordingly, a synthetic gene wasdesigned based on the amino acid sequence of gp85. The construct(gp85_wt) was wild-type amino acid sequence [SEQ ID NO: 2],codon-optimized for feline, with flanking sequence appropriate forcloning into the alphavirus replicon plasmid.

The VEE replicon vectors designed to express FeLV gp85 were constructedas previously described [see, U.S. Pat. No. 9,441,247 B2; the contentsof which are hereby incorporated herein by reference in theirentireties], with the following modifications. The TC-83-derivedreplicon vector “pVEK” [disclosed and described in U.S. Pat. No.9,441,247 B2] was digested with restriction enzymes AscI and PacI. A DNAplasmid containing the codon-optimized open reading frame nucleotidesequence of the FeLV gp85 genes, with 5′ flanking sequence(5′-GGCGCGCCGCACC-3′) [SEQ ID NO: 9] and 3′ flanking sequence(5′-TTAATTAA-3′), was similarly digested with restriction enzymes AscIand PacI. The synthetic gene cassette was then ligated into the digestedpVEK vector, and the resulting clone was re-named “pVHV-FeLV gp85”. The“pVHV” vector nomenclature was chosen to refer to pVEK-derived repliconvectors containing transgene cassettes cloned via the AscI and PacIsites in the multiple cloning site of pVEK.

Production of TC-83 RNA replicon particles (RP) was conducted accordingto methods previously described [U.S. Pat. No. 9,441,247 B2 and U.S.Pat. No. 8,460,913 B2; the contents of which are hereby incorporatedherein by reference]. Briefly, pVHV replicon vector DNA and helper DNAplasmids were linearized with NotI restriction enzyme prior to in vitrotranscription using MegaScript T7 RNA polymerase and cap analog(Promega, Madison, Wis.). Importantly, the helper RNAs used in theproduction lack the VEE subgenomic promoter sequence, as previouslydescribed [Kamrud et al., J Gen Virol. 91(Pt 7):1723-1727 (2010)].Purified RNA for the replicon and helper components were combined andmixed with a suspension of Vero cells, electroporated in 4 mm cuvettes,and returned to OptiPro® SFM cell culture media (Thermo Fisher, WalthamMass.). Following overnight incubation, alphavirus RNA repliconparticles were purified from the cells and media by passing thesuspension through a ZetaPlus BioCap depth filter (3M, Maplewood,Minn.), washing with phosphate buffered saline containing 5% sucrose(w/v), and finally eluting the retained RP with 400 mM NaCl buffer.Eluted RP were formulated to a final 5% sucrose (w/v), passed through a0.22 micron membrane filter, and dispensed into aliquots for storage.Titer of functional RP was determined by immunofluorescence assay oninfected Vero cell monolayers.

Example 2 Comparative Efficacy and Safety of FeLV Vaccines in Cats

A vaccine comprising an alphavirus RNA replicon particle (RP) comprisingthe capsid protein and glycoproteins of the avirulent TC-83 strain ofVenezuelan Equine Encephalitis Virus (VEE) and encoding the FeLV viralglycoprotein (gp85), was formulated in 5% sucrose. The liquid vaccinewas frozen for storage before use. This vaccine was compared with acommercially available vaccine comprising a recombinant canary poxencoding FeLV, as shown in Table 1 below. Five groups of eight felinesubjects were vaccinated either with a single dose at 8-9 weeks, or in aprime/boost regimen of 8-9 weeks of age and then 21 days later. Thedoses for each experimental vaccinate group is provided in Table 1below.

TABLE 1 VACCINATION PROTOCOL Vaccinate No. of Vaccination Group AnimalsVaccine RP/dose Days 1 8 RP-FeLV 4.35 × 10⁸ 0, 21 2 8 RP-FeLV 3.55 × 10⁷0, 21 3 8 RP-FeLV  1.5 × 10⁸ 21 (one shot) 4 8 PureVax ® ^(#) Does notapply 0, 21 5 8 Placebo none 0, 21 ^(#) A vaccine containing arecombinant canary pox encoding FeLV sold by Merial ®

All cats were subcutaneously vaccinated with 1.0 mL of their respectivevaccine regimen. Cats were 8-9 weeks of age at the time of the initialvaccination (including cats in Group 3). The cats of Group 4 werevaccinated at the times provided with the quantity of vaccine asdirected on the label of the commercial vaccine. Following thevaccination the cats were observed for adverse reactions to the vaccinesby observing the general health daily, as well as palpating the site ofinjection for the two days following each vaccination and twice per weekfor two weeks following each vaccination. No adverse reactions wereobserved for any of the vaccines.

All cats were challenged with a virulent culture of FeLV four weeksafter the booster vaccination (four weeks after the one-shot vaccinationfor the Group 3 cats). The cats were challenged on four separate daysover one week (study days 49, 52, 54 and 56) by administering 1.0 mL ofchallenge virus by the oronasal route (0.3 mL in each nostril and 0.4 mLorally). Three weeks after challenge serum samples were collected eachweek through ten weeks post-challenge. Serum samples were tested byELISA for the presence of FeLV p27 antigen. An animal is consideredinfected with FeLV if it is persistently antigenemic. Antigenemia isdefined as a positive p27 ELISA result for three consecutive weeks or onfive or more occasions during the eight week testing period. An FeLVvaccine must protect 75% of the cats vaccinated with the test productfor USDA licensure. In addition, in order for the challenge to beregarded as valid, 80% of the control cats must be persistentlyantigenemic [see, Shipley et al., JAVMA, Vol. 199, No. 10, (Nov. 15,1991)]. The results of the challenge are summarized in the Table 2below.

TABLE 2 VACCINATION AND CHALLENGE Treatment % Cats % Cats Group VaccineRP dose Antigenemic Protected 1 RP-FeLV 4.35 × 10⁸  0% 100%  2 RP-FeLV3.55 × 10⁷  0% 100%  3 RP-FeLV  1.5 × 10⁸ 13% 87% (one shot)* 4PureVax ® ^(#) Does not apply 43% 57% 5 Placebo Does not apply 88% 12%^(#) A vaccine containing a recombinant canary pox encoding FeLV sold byMerial ® *All other groups received a two-dose regimen, see, Table 1above.

As Table 2 demonstrates, the RP-FeLV vaccines protected 100% of the catswhen administered in a two-dose regimen (i.e., primary and boostervaccination) at both doses tested. Moreover, the RP-FeLV vaccineprotected 87% of the cats when administered as a single dose. In directcontrast, the commercially available vaccine only protected 57% of thecats, even with a two-dose regimen. In addition, the challenge isregarded as valid because greater than 80% of the control cats werepersistently antigenemic [see, Table 2]. Finally, all of the RP-FeLVvaccine formulations were found safe in cats.

Example 3 Determination of the Dose Dependence of an RP-FeLV Vaccine byVaccination and Challenge

The RP-FeLV vaccine of Example 2 was formulated in a vaccine formulationthat included enzymatically hydrolyzed casein (NZ-amine), gelatin, andsucrose. The vaccine was then lyophilized. Four groups of ten cats eachwere vaccinated as summarized in Table 3 below:

TABLE 3 VACCINATION PROTOCOL Treatment No. of Vaccination Group AnimalsVaccine RP/dose Days 1 10 RP-FeLV 1.1 × 10⁵ 0, 21 2 10 RP-FeLV 2.1 × 10⁶0, 21 3 10 RP-FeLV 6.5 × 10⁷ 0, 21 4 10 Non-vaccinated None NA Controls

All cats were vaccinated with 1.0 mL of respective test product,subcutaneously. The cats were 8-9 weeks of age at the time of initialvaccination. Following the vaccination the cats were observed foradverse reactions to the vaccines by observing their general dailyhealth, as well as palpating the site of injection for the two daysfollowing each vaccination and twice per week for the two weeksfollowing each vaccination. No adverse reactions to any of the vaccineswere observed.

All of the cats were challenged with a virulent culture of FeLV threeweeks after the booster vaccination. Cats were challenged on fourseparate days over one week (study days 42, 45, 47 and 49) byadministering 1.0 mL of challenge virus by the oronasal route (0.3 mL ineach nostril and 0.4 mL orally). Three weeks after challenge serumsamples were collected each week through twelve weeks post-challenge.Serum samples were tested by ELISA for the presence of FeLV p27 antigen.An animal is considered infected with FeLV if it is found to bepersistently antigenemic. Antigenemia is defined as a positive p27 ELISAresult for three consecutive weeks, or on five or more occasions duringthe eight-week testing period. For USDA licensure an FeLV vaccine mustprotect 75% of the cats vaccinated with the test product. For thechallenge to be considered valid, 80% of the control cats must bepersistently antigenemic [Shipley et al., JAVMA, Vol. 199, No. 10, Nov.15, 1991]. The results of the challenge are summarized in the Table 4below:

TABLE 4 DOSE DEPENDENCE OF RP-FELV Treatment % Cats % Cats Group VaccineRP/dose Antigenemic Protected 1 RP-FeLV 1.1 × 10⁵ 10%  90% 2 RP-FeLV 2.1× 10⁶  0% 100% 3 RP-FeLV 6.5 × 10⁷  0% 100% 4 Non-vaccinated None 90% 10% Controls

In this study of short term immunity, the minimum protective dose of theRP-FeLV vaccine for 100% protection of the cats was between about1.0×10⁵ to about 2.0×10⁶ RPs, when administered in a two dose (primaryand booster vaccination) regimen. The challenge was valid because atleast 80% of the control cats were persistently antigenemic. All RP-FeLVvaccine formulations tested were safe in cats.

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described herein will become apparent tothose skilled in the art from the foregoing description. Suchmodifications are intended to fall within the scope of the appendedclaims.

It is further to be understood that all base sizes or amino acid sizes,and all molecular weight or molecular mass values, given for nucleicacids or polypeptides are approximate, and are provided for description.

1. An immunogenic composition comprising an alphavirus RNA repliconparticle that encodes a feline leukemia virus (FeLV) antigen.
 2. Theimmunogenic composition of claim 1, wherein the alphavirus RNA repliconparticle is a Venezuelan Equine Encephalitis (VEE) alphavirus RNAreplicon particle.
 3. The immunogenic composition of claim 1, whereinthe FeLV antigen is a FeLV glycoprotein (gp85) or an antigenic fragmentthereof.
 4. The immunogenic composition of claim 3, that comprises oneor more additional alphavirus RNA replicon particles that encode asecond FeLV antigen which originates from a different strain of FeLVthan the one from which the FeLV antigen originates from.
 5. Theimmunogenic composition of claim 4, wherein the second FeLV antigen is aFeLV glycoprotein (gp85) or an antigenic fragment thereof.
 6. Theimmunogenic composition of claim 4, wherein the one or more additionalalphavirus RNA replicon particles are VEE alphavirus RNA repliconparticles.
 7. The immunogenic composition of claim 3, wherein the FeLVglycoprotein (gp85) comprises an amino acid sequence comprising at least95% identity with the amino acid sequence of SEQ ID NO:
 2. 8. Theimmunogenic composition of claim 3, wherein the antigenic fragment ofthe FeLV glycoprotein (gp85) is FeLV (gp70).
 9. The immunogeniccomposition of claim 8, wherein the FeLV gp70 comprises an amino acidsequence comprising at least 95% identity with the amino acid sequenceof SEQ ID NO:
 4. 10. A vaccine to aid in the prevention of disease dueto FeLV comprising the immunogenic composition of claim 3, and apharmaceutically acceptable carrier.
 11. The vaccine of claim 10,wherein an antibody is induced in a feline when said feline is immunizedwith the vaccine.
 12. The vaccine composition of claim 10 that furthercomprises at least one non-FeLV antigen for eliciting protectiveimmunity to a non-FeLV feline pathogen.
 13. The vaccine of claim 12,wherein the non-FeLV feline pathogen is selected from the groupconsisting of feline herpesvirus (FHV), feline calicivirus (FCV), felinepneumovirus (FPN), feline parvovirus (FPV), feline infectiousperitonitis virus (FIPV), feline immunodeficiency virus, borna diseasevirus (BDV), feline influenza virus, feline panleukopenia virus (FPLV),feline coronavirus (FCoV), feline rhinotracheitis virus (FVR),Chlamydophila felis, and any combination thereof.
 14. The vaccine ofclaim 13, wherein the non-FeLV antigen is a killed or attenuatednon-FeLV antigen selected from the group of killed or attenuatednon-FeLV antigens consisting of feline herpesvirus (FHV), felinecalicivirus (FCV), feline pneumovirus (FPN), feline parvovirus (FPV),feline infectious peritonitis virus (FIPV), feline immunodeficiencyvirus, borna disease virus (BDV), feline influenza virus, felinepanleukopenia virus (FPLV), feline coronavirus (FCoV), felinerhinotracheitis virus (FVR), Chlamydophila felis, and any combinationthereof.
 15. The vaccine of claim 14, wherein the attenuated non-FeLVantigen is a modified live feline pathogen selected from the groupconsisting of a modified live Chlamydophila felis, a modified livefeline rhinotracheitis Virus (FVR), a modified live feline calicivirus(FCV), a modified live feline panleukopenia virus (FPL), a modified livefeline herpesvirus (FHV), a modified live feline pneumovirus (FPN), amodified live feline parvovirus (FPV), a modified live feline infectiousperitonitis virus (FIPV), a modified live feline immunodeficiency virus,a modified live borna disease virus (BDV), a modified live felinecoronavirus (FCoV), and a modified live feline influenza virus.
 16. Thevaccine composition of claim 10, that further comprises an alphavirusRNA replicon particle comprising a nucleotide sequence encoding at leastone protein antigen or an antigenic fragment thereof that originatesfrom a non-FeLV antigen.
 17. The vaccine of claim 16, wherein theprotein antigen or an antigenic fragment thereof that originates from anon-FeLV feline pathogen selected from the group consisting of felineherpesvirus (FHV), feline calicivirus (FCV), feline pneumovirus (FPN),feline parvovirus (FPV), feline infectious peritonitis virus (FIPV),feline immunodeficiency virus, borna disease virus (BDV), felineinfluenza virus, feline panleukopenia virus (FPLV), feline coronavirus(FCoV), feline rhinotracheitis virus (FVR), Chlamydophila felis, and anycombination thereof.
 18. The vaccine composition of claim 10, that is anonadjuvanted vaccine.
 19. A method of immunizing a feline against apathogenic FeLV comprising administering to the feline animmunologically effective amount of the vaccine of claim 18.